The Tuatha Dé Danann remained masters of Ireland until the coming of the Milesians, so named from an eponymous Mile, son of Bile. Ith, having been sent to reconnoitre, was slain, and the Milesians now invaded Ireland in force. In spite of a mist raised by the Druids, they landed, and, having met the three princes who slew Ith, demanded instant battle or surrender of the land. The princes agreed to abide by the decision of the Milesian poet Amairgen, who bade his friends re-embark and retire for the distance of nine waves. If they could then effect a landing, Ireland was theirs. A magic storm was raised, which wrecked many of their ships, but Amairgen recited verses, fragments, perhaps, of some old ritual, and overcame the dangers. After their defeat the survivors of the Tuatha Dé Danann retired into the hills to become a fairy folk, and the Milesians (the Goidels or Scots) became ancestors of the Irish.
Throughout the long story of the conquests of Ireland there are many reduplications, the same incidents being often ascribed to different personages.122 Different versions of similar occurrences, based on older myths and traditions, may already have been in existence, and ritual practices, dimly remembered, required explanation. In the hands of the chroniclers, writing history with a purpose and combining their information with little regard to consistency, all this was reduced to a more or less connected narrative. At the hands of the prosaic chroniclers divinity passed from the gods, though traces of it still linger.
"Ye are gods, and, behold, ye shall die, and the waves be upon you at last.
In the darkness of time, in the deeps of the years, in the changes of things,
Ye shall sleep as a slain man sleeps, and the world shall forget you for kings."
From the annalistic point of view the Fomorians are sea demons or pirates, their name being derived from muir, "sea," while they are descended along with other monstrous beings from them. Professor Rh^ys, while connecting the name with Welsh foawr, "giant" (Gaelic famhair), derives the name from fo, "under," and muir, and regards them as submarine beings.123 Dr. MacBain connected them with the fierce powers of the western sea personified, like the Muireartach, a kind of sea hag, of a Fionn ballad.124 But this association of the Fomorians with the ocean may be the result of a late folk-etymology, which wrongly derived their name from muir. The Celtic experience of the Lochlanners or Norsemen, with whom the Fomorians are associated,125 would aid the conception of them as sea-pirates of a more or less demoniacal character. Dr. Stokes connects the second syllable mor with mare in "nightmare," from moro, and regards them as subterranean as well as submarine.126 But the more probable derivation is that of Zimmer and D'Arbois, from fo and morio (mor, "great "),127 which would thus agree with the tradition which regarded them as giants. They were probably beneficent gods of the aborigines, whom the Celtic conquerors regarded as generally evil, perhaps equating them with the dark powers already known to them. They were still remembered as gods, and are called "champions of the síd," like the Tuatha Dé Danann.128 Thus King Bres sought to save his life by promising that the kine of Ireland would always be in milk, then that the men of Ireland would reap every quarter, and finally by revealing the lucky days for ploughing, sowing, and reaping.129 Only an autochthonous god could know this, and the story is suggestive of the true nature of the Fomorians. The hostile character attributed to them is seen from the fact that they destroyed corn, milk, and fruit. But in Ireland, as elsewhere, this destructive power was deprecated by begging them not to destroy "corn nor milk in Erin beyond their fair tribute."130 Tribute was also paid to them on Samhain, the time when the powers of blight feared by men are in the ascendant. Again, the kingdom of Balor, their chief, is still described as the kingdom of cold.131 But when we remember that a similar "tribute" was paid to Cromm Cruaich, a god of fertility, and that after the conquest of the Tuatha Dé Danann they also were regarded as hostile to agriculture,132 we realise that the Fomorians must have been aboriginal gods of fertility whom the conquering Celts regarded as hostile to them and their gods. Similarly, in folk-belief the beneficent corn-spirit has sometimes a sinister and destructive aspect.133 Thus the stories of "tribute" would be distorted reminiscences of the ritual of gods of the soil, differing little in character from that of the similar Celtic divinities. What makes it certain that the Fomorians were aboriginal gods is that they are found in Ireland before the coming of the early colonist Partholan. They were the gods of the pre-Celtic folk—Firbolgs, Fir Domnann, and Galioin134—all of them in Ireland before the Tuatha Dé Danaan arrived, and all of them regarded as slaves, spoken of with the utmost contempt. Another possibility, however, ought to be considered. As the Celtic gods were local in character, and as groups of tribes would frequently be hostile to other groups, the Fomorians may have been local gods of a group at enmity with another group, worshipping the Tuatha Dé Danaan.
The strife of Fomorians and Tuatha Dé Danann suggests the dualism of all nature religions. Demons or giants or monsters strive with gods in Hindu, Greek, and Teutonic mythology, and in Persia the primitive dualism of beneficent and hurtful powers of nature became an ethical dualism—the eternal opposition of good and evil. The sun is vanquished by cloud and storm, but shines forth again in vigour. Vegetation dies, but undergoes a yearly renewal. So in myth the immortal gods are wounded and slain in strife. But we must not push too far the analogy of the apparent strife of the elements and the wars of the gods. The one suggested the other, especially where the gods were elemental powers. But myth-making man easily developed the suggestion; gods were like men and "could never get eneuch o' fechtin'." The Celts knew of divine combats before their arrival in Ireland, and their own hostile powers were easily assimilated to the hostile gods of the aborigines.
The principal Fomorians are described as kings. Elatha was son of Nét, described by Cormac as "a battle god of the heathen Gael," i.e. he is one of the Tuatha Dé Danann, and has as wives two war-goddesses, Badb and Nemaind.135 Thus he resembles the Fomorian Tethra whose wife is a badb or "battle-crow," preying on the slain.136 Elatha's name, connected with words meaning "knowledge," suggests that he was an aboriginal culture-god.137 In the genealogies, Fomorians and Tuatha Dé Danann are inextricably mingled. Bres's temporary position as king of the Tuatha Déa may reflect some myth of the occasional supremacy of the powers of blight. Want and niggardliness characterise his reign, and after his defeat a better state of things prevails. Bres's consort was Brigit, and their son Ruadan, sent to spy on the Tuatha Dé Danann, was slain. His mother's wailing for him was the first mourning wail ever heard in Erin.138 Another god, Indech, was son of Déa Domnu, a Fomorian goddess of the deep, i.e. of the underworld and probably also of fertility, who may hold a position among the Fomorians similar to that of Danu among the Tuatha Dé Danann. Indech was slain by Ogma, who himself died